Forgeability of Wang-Tang-Li's ID-Based Restrictive Partially Blind Signature Scheme

• 作 者: 刘胜利 陈晓峰 张方国
• 机 构: Department of Computer Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China S
• 出 处: Journal of Computer Science & Technology
• 发表日期: 2008年02期
• 关键词: signature restrictive dangerous signer instead blind satisfy claimed agreed secu

Restrictive partially blind signature(RPBS)plays an important role in designing secure electronic cash system. Very recently,Wang,Tang and Li proposed a new ID-based restrictive partially blind signature(ID-RPBS)and gave the security proof.In this paper,we present a cryptanalysis of the scheme and show that the signature scheme does not satisfy the property of unforgeability as claimed.More precisely,a user can forge a valid message-signature pair(ID,msg,info’,σ’) instead of the original one(ID,msg,info,σ),where info is the original common agreed information and info’≠info. Therefore,it will be much dangerous if Wang-Tang-Li’s ID-RPBS scheme is applied to the off-line electronic cash system. For example,a bank is supposed to issue an electronic coin(or bill)of $100 to a user,while the user can change the denomination of the coin(bill)to any value,say $100000000,at his will.

Very recently, Wang, Tang and Li proposed a new ID-based restrictive partially blind signature (ID-RPBS) and gave the security proof. In this paper , we present a cryptanalysis of the scheme and show that the signature scheme does not satisfy the property of unforgeability as claimed .More precisely, a user can forge a valid message-signature pair (ID, msg, info ’, σ’) instead of The original one (ID, msg, info, σ), where info is the original common agreed information and info ’≠ info. Thus, it will be much more if if-Tang-Li’s ID-RPBS scheme is applied to the off- For example, a bank is supposed to issue an electronic coin (or bill) of $ 100 to a user, while the user can change the denomination of the coin (bill) to any value, say $ 100000000, at his will .